postgresql7.1
select object_type as ancestor_rel_type
from acs_object_types
where supertype = 'relationship'
and object_type in (
select t2.object_type
from acs_object_types t1, acs_object_types t2
where t1.object_type = :add_with_rel_type
and t1.tree_sortkey between t2.tree_sortkey and tree_right(t2.tree_sortkey)
)